It is well known that crops such as corn and soybeans grow best in soil that is loose, rich in nutrients, and free of debris. After a crop is harvested, the soil is often compacted, depleted of nutrients, and full of crop residue and other debris. To restore the soil to optimal conditions, the soil is often tilled immediately before planting. Tilling is also known as cultivating or plowing (also spelled “ploughing”). The soil may also be tilled immediately after harvest. The conventional method of tillage is to treat the entire field. More recently, it has become popular to treat only the narrow strips of soil that will contain the seed rows. This method of tillage is commonly known as strip tillage or zone tillage. Strip tillage saves time and energy and reduces erosion.
Strip tillage is performed by driving a tractor through the field pulling a wheeled toolbar to which multiple row implements are attached. The row implements are spaced apart to correspond to the seed rows that will be planted. A conventional row implement is shown in FIGS. 1 and 2. The direction of movement of the row unit is from left to right as indicated by the large straight arrow. The row implement 10 contains a frame 20 with a bracket 21 or other suitable means for attachment to a toolbar. Attached to the frame are two cleaning disks 30 to clear crop residue and other debris, two or three scoring disks 40 (also spelled “discs” and also known as colters or coulters) to break the surface of the ground, and two depth wheels 50 attached to the outer scoring disks to control the vertical position of the row implement relative to the ground. Each scoring disk, with or without an attached depth wheel, rotates independently. Scoring disks are substantially flat or contain waves, ripples, or other protrusions and indentations.
The conventional row unit shown in FIGS. 1 and 2 also contains a knife 60 attached to a shank to create a trench (also known as a furrow) in the soil into which the fertilizer is applied and/or into which the seeds are deposited if planting is being conducted, a tube 70 to apply fertilizer and/or seeds into the trench, and two closing disks 80 to fill in the trench to create a raised berm where the trench had been formed. Many implements also contain one or more tamping wheels 90 at the rear that tamp the berm to the desired density and cross section. The tamping wheel shown is disclosed in Rosenboom, U.S. Pat. No. 9,516,803, Dec. 13, 2016.
A variety of row implements have been disclosed, including Roggenbuck et al., U.S. Pat. No. 5,333,694, Aug. 2, 1994; Thompson et al., U.S. Pat. No. 5,520,125, May 28, 1996; Kovach et al., U.S. Pat. No. 6,761,120, Jul. 13, 2004; Neudorf et al., U.S. Pat. No. 7,213,523, May 8, 2007; and Ankenman, U.S. Pat. No. 7,866,270, Jan. 11, 2011.
As previously mentioned, row implements contain a means for controlling the position of the row implement relative to the ground, i.e., for controlling the depth the scoring disks and knife penetrate into the ground. The means for controlling the position is generally a pair of depth wheels. The depth wheels are generally steel concentric rings that are bolted or otherwise attached to the sides of the scoring disks. Depth wheels attached to independently rotating scoring disks suffer from two problems. First, trash tends to build up along the right angle corner where the depth wheel meets the scoring disk. Second, the independently rotating scoring disks with attached depth wheels tend to skid rather than rotate, especially in wet fields or fields having a large amount of trash. As they skid, trash builds up and causes plugging in and between the row implements.
Some row implements contain freely rotating, pneumatic (air filled) rubber depth wheels. The disadvantage of pneumatic rubber depth wheels is that they wear out and must be replaced periodically. Other row implements contain freely rotating steel depth wheels that are not attached to the scoring disks. The disadvantage of these independently rotating steel depth wheels is that they tend to skid rather than rotate. As they skid, trash builds up and causes plugging in and between the row implements.
Accordingly, there is a demand for a row implement with an improved depth wheel. More particularly, there is a demand for a row unit with depth wheels that are less likely to skid and cause a build up of trash.